Ventilated excavator cab



Oct. ll', 1949. w. s. BuRDlKAETAL vENTILMEb-fExcAvATon CAB Filed April 19', 1945 IN VENTOR.

Afro/MEX Oct. ll, 1949. w. s. BURDlcK E'rAL VENTILATED EXCAVATOR CAB s shtsfsheet 2 Filed April 19, 1945 s OI A' INVENToR.

v wrom/y Patented Oct. 11, 1949 VEN TILATED EXCAVATOR CAB Will S. Burdick, Wauwatos Milwaukee, Wis.,

assignors and Henry S. Jacobs, to Harnischfeger Corporation, Milwaukee, Wis., a corporation of Wisconsin Application April 19, 1945, Serial No. 589,188

3 Claims.

The invention relates to power operated excavators and more particularly to the heat dissipating arrangements for the cab mounted power units thereof and resides more particularly in a 'form of such apparatus in which a continually renewed atmosphere of filtered air under pres- 'sure is maintained within said cab by forcing means while continually permitting the same to escape after first passing over heat dissipating surfaces of electrical or other power units contained within the cab and requiring cooling.

Excavators are usually provided with cabs or enclosures for protecting the machinery from the weather. In hot weather the sun beating down on the cab of the ordinary excavating machine may raise the temperature of the air within the cab to a point where the operating temperatures of power units such as electric motors and the like becomes so high that there is danger of deterioration of the windings, particularly where the overload capacity oi such power units may be small. Furthermore, excavators have to work in locations where a large amount of dust and abra- 'sive matter is brought into suspension in the air ,which if given free access to the cab may cause `damage to operating parts contained therein. `The object of this invention is to provide an apparatus which permits a ltered air supply to be fforced through the cab to escape channels con- ',taining instrumentalities to be cooled, at such a frate that the temperature rise within the cab due to sun load will be held within moderate limits and a pressure substantially in excess of outside pressure will be maintained, so that all air movement through accidental aswell asintendfed unltered openings in the cab will be out'- wardly thus precluding the entrance of dust laden unltered air.

A further object of the invention is to provide 4an excavator having a cab containing moving air under pressure and 1n which, in case the system to operate, the source of electrical energy for operating the electrical units within the cab will ybe shut olf. 'f

v The invention further consists in the several features hereinafter set forth and more particularly defined by claims at the conclusion hereof.

In the drawings: f

Fig. 1 is a side elevation view of an excavator embodying the invention, `parts being broken away and parts being shown in section;

y Fig. 2 is a plan view of the excavator, parts being broken away and parts being shown as a -oor plan of the cab;

'is provided with air inlets Fig. 3 is a detailed vertical sectional view taken on the line 3--3 of Fig. 1;

Fig. 4 is a detailed vertical sectional view taken on the broken line 4 4 of Fig. 1;

Fig. 5 is an end elevation view of the clutch, parts being broken away and parts being shown in section;

Fig. 6 is a diagrammatic view of otherrprotective means for the main circuit supply wiring and control.

Referring to the drawings, the excavator includes a traveling base 6 supported on endless propelling treads 6 suitably driven from the rotating base 8 which has the boom 'I pivotally supported therefrom at one end. The base 8 is mounted in known manner to swing or rotate on the base 6 so as to position the boom 'l in the desired working position.

The platform 9 of the base 8 has the excavator operating units mounted thereon and is enclosed -by a cab I0 which is provided with pressure sealed inwardly opening doors II and I 2y the door I2 providing access to the operators compartment I3 which has an inwardly opening door I4 and exterior steps I5 leading thereto. The space housing the operating units is completely enclosed by the cab, so that the air therein may be maintained under a pressure somewhat above atmospheric pressure and air is supplied thereto by a forcing fan I 6 driven by an electric motor I1 and located in an apertured conduit I8 mounted adjacent the roof I9 of the cab at its back end air through a transversely disposed inlet conduit 20 having louvered entrances 2| at each side of the cab and having air filtering units 22 therein mounted on a suitable framework 23 and accessible for installation and removal through a top opening 24 normally closed vby a removable cover 25.

The operating units may include a pair of generators 26, a drive electric motor 21 therefor, a 'swing motor 28, a propelling motor `29, a hoist -motor operatively connected through an eddy current clutch mechanism 3I and gearing 32 with a hoist drum 33.

For cooling the generators 26, their housing 34 35, and the exhaust lfrom each end 38 of this housing connects with an outlet or discharge conduit 3l extending to the vexterior through the rotatable base 8. The swing 'and propell motors are similarly cooled, and as shown in detail in Fig. 1, the housing 38 of the propell motor has airinlets 39 and an exhaust fopening 4I) connected by a conduit 4I to a passage -42 extending to the interior through the base 8.

The housing 43 for the eddy current clutch mechanism 3| is provided with an apertured inlet 44 and an exhaust through a discharge conduit 45 extending to the exterior through the base The housing 46 for the hoist motor 30 has an axial air inlet similar to the inlet 44 and exhausts through peripheral openings 4l into a casing 48 similar to the housing 43 that has a discharge (not shown) through the base 8 similar to the discharge 45. motor 3U may be used in conjunctionuwith the drive motor 2l', but it has been iound that with the forced cooling herein described one ormore oi the power units may be cooledin conventional fashion by recirculation of the ambient air without danger of overheating of such unit, particularly since such ambient air is subject to continuous positive renewal. t is also to'bel noted'that in connection with the swing motor 28 the'exhast conduit 49 therefrom similar to the conduit 4l of lthepropell motor, discharges through anopening in the side wall of the cab directly to atmosphere adjacent a small operators platform `50. rIfhe several units arer thus provided with forced flow .cooling by a continually renewed, ing air.

The hoisting cables 5l pass up through openings (not shown) in the roof of thecab and Yout toappropriate connections, with the gear on the boom. Where the cable passes through these openings, boots or slidesmay be usedor open slots of no greater magnitude than is required for the proper reaving and movement oi the cable can be used since the fan I6 may be designed to have a capacity sufficient to allow `for a certain :i

amount oi air leakage through theseslots without loss of the desired pressure within the cab.

The operators compartment i3 contains the operators seat 52, the. electric hand controls 53,

and the foot controls 54, Since door l2 is normally kept closed and a certain amount oi air leaks through the various openings provided such as for the ioot controls, the pressure within compartment i3 is at substantially atmospheric pressure, and compartment 'i3 is Iconnected to the relatively higher pressure cab enclosurelil by a small passage 55 which is locatedadjacent the thermal responsive element 56 of a thermal overload switch 5? that is included in the relay circuit 53 for the relay 5% Vcontrolling, the main load switch Gil. Thermo-responsive element 55 is of well known type containing aheating coil, so that failure ci the forced air stream passing through opening will permit temperature to rise in element to the tripping point even though a .low ambient temperature is prevailing. The relay .circuit also includes the manually controlled 'start and stop push buttons 6l and 62. .The'j thermal overload cut out switch 51 with its thermal sensitive element 55 is locatedk in a position so that it will respond to the temperature of the air in the cab lil and the rate at which such air escapes through opening Thus if for any` reason insulicient air is being supplied to the cab to maintain rapid ilow through opening 55 and conse.- quently through the other escape channels, so that suiiicient cooling for the proper operation of the units within the calo is not provided, the switch mechanism 5l operates to cut out the relay circuit 55 and cause switch til to stop the entire operation of the machine until the diiriculty with the air supply system can ce remedied.

It will be noted that this switch mechanism is ,housed within` a` compartmentA 53 hayingan aper- This same method of cooling the,l

stream of ccolthe opening of the main tured inlet 64 and discharging through the small outlet 55 into the operators compartment i3 which as noted has outlet openings, so that there is a constant circulation 0I air from the cab past the thermal responsive element 55.

With the above arrangement the iiltering elements remove the dustl and dirt, from the air furnished to the cab interior and thus prevent this foreign matter from getting into the bearings of the operating units and at the same time the vforced circulation of air through the cab and its directional flow through parts of the operating units acts to carry off heat generated by l theseunits -andkeep them at an efficient operating temperature,

thus increasing the over all life of the machine and'over all efficiency of the operating` units.

We desire it to be understood that this invention is not to be limited to any particular form or arrangement of parts except in so far as Such limitations are included in the claims.

What we claim as our invention is:

l. In an excavator having a cab enclosing its motive power operating unita'an inlet opening through thewall oi said cab, a filter interposed in said inlet opening, a fan disposed in said inlet opening adapted to draw air in tliroughsaid inlet opening and to cause said air towflcw through said filter and to discharge said filtered air within said cab against a pressure in excess of atmospheric pressure, housings for saidoperating units surrounding the same and having inletopenings within said cab and escape passages extending to the exterior or" saidcab forming with said'roperating units cooling channels through which ,forced cooling streams of airare caused' to pass in heat removing relationship to saidA operating .units while escaping with a drop in pressure from said cab `when said fan is Qperating, saidcab being substantially closed save for incidental openings and save for said ltered inlet opening and said now resisting escape passages whereby an inlfiltration-precluding `positive pressure is maintained within said cahwhen said fan is operating.

2. In an electrically operated excavator having a cab enclosing its electricpower operating units,

fan inlet opening through the wall of said cab, a.

filter in said inlet opening, an electrically driven fan adapted to draw air into said inlet opening and to discharge said air within said cab while passing through said filter, housings for said electric power units surrounding the same and having inlet openings within said cabl and escape passagesextending to the exterior of Said cab fcrmingwith said electric power units cooling channels through which forcedfstreams of cooling air are caused to pass in heat removing relationship to said electric power units in escaping from saidV cab when said fan is operating, said cab being substantially `closed save for lncidental'openings and save for said inlet open- 'ing and saidy Yescape passages whereby Va`ri`kwin ltration-precluding positive pressure is maintained within said cab when said vian is operating, a power supply forl said electric power units, power supply maintaining means adapted' to maintain the same while positive pressure 'prevails within said cab and adapted to interrupt said supply upon failure of said pressure.

3. In an'electrically operated excavator having a cab enclosing its electric power operating units, an inlet opening through the wall of said cab, an electrically driven ian adapted" to vdravv'air into said inlet opening and to discharge sai'd air Within said cab, said inlet opening including means adapted to cause the stream of air delivered to said fan to be comparatively free of dust, housings for said electric power units surrounding the same and having inlet openings within said cab forming with said electric power units cooling channels through which forced streams of cooling air are caused to pass in heat removing relationship to said electric power units in escaping from said cab when said fan is operating, said cab being substantially closed save for incidental openings and save for said inlet opening and said escape passages whereby an infiltration-precluding positive pressure is maintained within said cab when said fan is operating, a power circuit for said electric power units, a control escape opening in a wall of said cab through which a control stream of cooling air may escape under the impetus of pressure prevailing in said cab, a temperature responsive circuit maintaining instrumentality positioned to be impinged by said control stream and adapted to open said power circuit upon attaining a predetermined temperature in excess of normal operating temperature, and heating means in heat transmitting relationship to said circuit mainftaining instrumentality adapted to cause the same to be heated to a temperature exceeding said predetermined temperature only upon failure of said control stream to normally cool the same.

WILL S. BURDICK.

HENRY S. JACOBS.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,315,996 Simmon Sept. 16, 1919 1,751,686 Duerk Mar. 25, 1930 1,796,198 Gehnrich Mar. 10, 1931 1,859,797 Ready May 24, 1932 1,898,859 Thorp Feb. 21, 1933 1,987,456 Woodard Jan. 8, 1935 2,203,477 Wahlberg June 4, 1940 2,289,910 Hanson July 14, 1942 2,292,192 Bergstrom Aug. 4, 1942 2,300,418 Hall Nov. 3, 1942 

